In the past year, 30 Tibetans have set themselves on fire in protest at Chinese rule. But what has prompted this fresh wave of self-immolations and what causes them to vent their political anger in such an extreme way?

You might not have heard of Thich Quang Duc but you have almost certainly seen a picture of him.

He was the Vietnamese Buddhist monk who set himself on fire – an act known as self-immolation – in 1963 in protest at the persecution of Buddhists by South Vietnam’s Roman Catholic government.

A photo of his death appeared on the cover of Rage Against The Machine’s debut album in 1992. Now, almost 50 years after Thich Quang Duc died, a fresh wave of self-immolations is rocking Tibet.

Since March last year, at least 30 Tibetans have self-immolated in protest at China’s rule of Tibet, with 20 taking place since the start of 2012.

The locations also hint at the increasing desperation felt by Tibetans. While the majority have taken place in Ngaba – the autonomous Tibetan prefecture in Sichuan – self-immolations are no longer confined to Tibet.

Jamphel Yeshi, a young Tibetan living in Delhi, set himself on fire during a protest against Chinese president’s Hu Jintao’s visit to the city last month.

He died two days later. Self-immolations are also no longer carried out only by monks. Tenzin Wangmo became the first nun to self-immolate in October. ‘We’ve recently had a mother of four who chose to give her life and a schoolgirl – ordinary Tibetans from different backgrounds and age groups,’ said Stephanie Brigden, director of Free Tibet.

‘It’s a pattern of protests which started in March 2011 and which we can now confidently refer to as the Tibetan Spring.’ But why is this happening now?

Experts point to the upcoming change in leadership and the fact that the Chinese government is increasingly cracking down on protests and becoming ever keener to exert its authority in Tibet.

‘Later this year there’ll be the change of leadership, which is causing great unrest and uncertainty because the government will do everything in its power to hand over a legacy of a stable country.’

The approach of those who choose this form of protest is far from haphazard.

Sonam Dargye self-immolated last March. The previous night, he travelled to the Tibetan town of Rongwo and checked into a hotel. The next morning he washed and prayed before drinking petrol. He left the hotel and shouted, ‘Let his holiness return to Tibet’, before setting himself on fire.

It is this considered approach which makes self-immolation such an effective way of protesting, according to Prof John G Horgan, a terrorism expert and psychology professor at Pennsylvania State University.

‘For the monks, legitimacy is key to their survival,’ he said. ‘For political or religious terrorists, suicide bombing is ultimately self-defeating.

‘It’s a stepping stone to popularity in the short term and a powerful tactic to get one’s group on to the same playing field as the more notorious terrorist groups, but eventually leads to a loss in support.

‘Those who self-immolate are undoubtedly aware that a suicide in which others are murdered will ultimately lead to the demonisation of the group.’

In the same way that Thich Quang Duc’s self-immolation was captured by a press photographer in 1963, today’s deaths are caught on mobile phones and sent electronically around the world.